Turbidity in Minnesota rivers is often blamed on surface intakes on Minnesota farms. So should we get rid of surface intakes? Just maybe there isn't nearly the amount of sediment runoff into surface inlets that most people assume. Dr. John Moncrief, U of M Dept of Soil, Water and Climate, says that when heavy rains produce field ponding that lasts for 6 hours or moe, about 80% of the particulates settle out. Convert that surface inlet to a gravel intake essentially eliminates all sediments into the tile system. So can proper pattern tiling over the farming landscape significantly 'clean up' Minnesota rivers and streams? Moncrief says 'yes'. He thinks a bigger source of turbidity is the sloughing off of stream banks, naturally occurring events triggered by high water fallowing intense rainfalls. And he questions that increased tiling is the 'culprit' behind the increased stream bank erosion. "The only water that flows through tile is the water between field capacity and saturation. And thanks to tiling, there is much more storage capacity in the soil to handle future rains. That is why good tiling sysems incrementally cut down on flooding occurrences." Perhaps pattern tiling is rebuilding fish populations also! Moncrief validates that water discharging from a pattern tiled field is definitely cooler than surface runoff into open inlets. And that is simply because soils at the 3' to 4' depth are much cooler than surface soils so tile at this depth cools the water running through those tile lines. "And it stands to reason that cooler water improves fish habitat." Stay tuned. The debates on tiling being a helpful improvment in our landscape are continuous. But science is slowing validating that good tiling improves soil productivity and reduces water turbidity. And just maybe is improving Minnesota River fishing too. Dick Hagen |
